The present invention relates to a semiconductor device and a method for manufacturing the same. Particularly, the present invention is concerned with a semiconductor device having a sealing ring which surrounds a chip region, as well as a method for manufacturing the semiconductor device.
There is known a semiconductor device having a sealing ring region formed so as to surround a chip region in plan to prevent the entry of water into the chip region in which an electric circuit is formed. The sealing ring region has a sealing ring formed on a substrate so as to extend in the thickness direction of the substrate. The sealing ring functions as a protection wall against water, whereby the entry of water into the chip region is suppressed.
There sometimes occurs a case where the sealing ring is destroyed in a dicing process during manufacture of a semiconductor device. This destruction phenomenon will be explained in regular order. First, the dicing operation causes chipping at an end portion of a substrate. With this chipping as a starting point, a crack is developed in an interlayer dielectric film formed on the substrate. When the crack reaches the sealing ring, there occurs destruction of the sealing ring. Once this destruction occurs, water is apt to get into the chip region, thus giving rise to the problem that the reliability of the semiconductor device is deteriorated.
This problem is more likely to occur when a low dielectric constant film formed of a low-k material or ULK (Ultra Low-k) material is used as an interlayer dielectric film to decrease parasitic capacitance. This is because the low-k or ULK material is low in mechanical strength and therefore a crack is more likely to occur. For example, in case of using Young's modulus as an index of mechanical strength, Young's modulus of SiO (silicon oxide), which is the material of a conventional interlayer dielectric film (non-low-k film), is 75 Gpa or so, while that of organic silica glass, which is one of low-k materials, is about 10 to 25 GPa. ULK material, which is a material rendered porous for attaining a still lower dielectric constant, has a smaller Young's modulus. Thus, in a semiconductor device using a low dielectric constant film, the destruction problem of the sealing ring caused by cracking is more likely to occur.
In a semiconductor device there often is adopted a configuration wherein on one interlayer dielectric film formed of a low dielectric constant material there is disposed another interlayer dielectric film of a higher mechanical strength. In this case, a crack developed in one interlayer dielectric film is difficult to expand into the other interlayer dielectric film having a higher mechanical strength. Consequently, the crack is difficult to advance upwards through the semiconductor device and it is apt to advance in the intra-plane direction of the substrate in the interior of the semiconductor device. As a result, the crack reaches the sealing ring and hence the possibility of the sealing ring being destroyed becomes still higher.
As described above, a crack developed in the interlayer dielectric film exerts a bad influence on the reliability of the semiconductor device. In view of this point there have been proposed techniques for suppressing the formation of a crack. For example, in Japanese Unexamined Patent Publication No. 2004-153015 (Patent Literature 1) it is proposed to form a dummy pattern-forming region around a guard ring (sealing ring). The dummy pattern-forming region has plural dummy patterns in each of plural places in plan. The plural dummy patterns are arranged in the thickness direction and are rendered integral by via coupling made in the thickness direction. According to the publication, since an interlayer dielectric film located near the dummy patterns can be reinforced by via coupling, the occurrence of a crack in the interlayer dielectric film is prevented.